Model for the prediction of noise from wind turbines

Abstract

This article presents a prediction model that can be applied to estimate the propagation of noise generated by wind turbines through an easy calculation procedure. The proposed prediction model is semi-empirical and based on the analysis of phenomena related to the generation and propagation of sound levels and field measurements. An experimental program was designed that included the measurement of sound pressure levels with a sound level meter to different weather conditions and distances within a wind farm to compare them with the levels estimated by ISO 9613 Part 2. A statistical analysis of the data recorded in field was performed to observe the dependence on the meteorological variables recorded during the measurements. The model explains 92.5% of the variability of the residual sound pressure level and has an average absolute error of 2.9 dB. After eliminating 5.0% of the data considered atypical, the proposed model explains 94.7% of the variability of the residual sound pressure level, with an average absolute error of 2.5 dB. A statistically significant relationship exists between the variables with a confidence level of 95.0%. The results have provided a rather satisfactory model for predicting noise from wind turbines up to distances of 900 m, greatly improving what has been achieved so far by the method established in standard ISO 9613 Part 2. literature for that particular subject.